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Proceedings Paper

Calculations of bandstructures on the lens and pyramid-shaped InAs quantum dot for confirming the photoluminescence and photoresponse
Author(s): Tzu-Huan Huang; Shiang-Feng Tang; Tzu-Chiang Chen; Fu-Fa Lu; Cheng-Der Chiang
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Paper Abstract

Electronic and optical properties of ideal and real quantum dots (QDs) are extensively studied and derived for the recent decade. Strain caused by the differences of the lattice constants of dot and wetting, barrier materials are decisive for both the self-assembly mechanisms and the electro-optical properties. The research is mainly investigated for realizing the strain effects on the optical properties of InAs/GaAs self-assembled QDs embedded in GaAs barrier layer incorporated with the three-dimensional (3D) Schördinger equation and solved by using finite element method (FEM). From 3D QD geometrical profiles establishing by the spatially geometric equations, the confined electron and hole bandstructures on altering sized lens and pyramidal shape-like QDs with numerical calculations and strained heterostructure of the finite element approximations have been proposed. Applying the fast FEM models, it is demonstrated that the correspondence of ground, excited eigenstates, the probability of density function (|Ψ|2) of the confined levels from the single InAs QD to a matrix of nine QDs to obtain the transition energy and coordinated absorption wavelength to be predicted and summarized clearly. Through calculating energy levels within the conduction and valence band edge confinement on the InAs/GaAs heterostructure with FEM to contradistinguish with corrected to optical transitions and linear absorption spectra can be achieved for verifying to being the specific wavelengths from photoluminescence (PL) and photoresponse (PR) measurements for quantum dot infrared photodetector. By fitting the energy differences among the subbands, the geometrical shape and size of QD can be predicted. Inducting the tendency from single QD to the matrix of 9 QDs, the step-wise bands have been obtained being some regularity clearly. And from the transmission electron microscope (TEM) measurement, the dominant sizes of QDs in the really grown wafer remain the consistent with the numerical analyses applied in 3D QD profile that is interpreted using spatially geometric equations.

Paper Details

Date Published: 3 February 2007
PDF: 9 pages
Proc. SPIE 6479, Quantum Sensing and Nanophotonic Devices IV, 64790G (3 February 2007); doi: 10.1117/12.698911
Show Author Affiliations
Tzu-Huan Huang, National Defense Univ. (Taiwan)
Shiang-Feng Tang, Chung-Shan Institute of Science and Technology (Taiwan)
Tzu-Chiang Chen, National Defense Univ. (Taiwan)
Fu-Fa Lu, Chung-Shan Institute of Science and Technology (Taiwan)
Cheng-Der Chiang, Chung-Shan Institute of Science and Technology (Taiwan)

Published in SPIE Proceedings Vol. 6479:
Quantum Sensing and Nanophotonic Devices IV
Manijeh Razeghi; Gail J. Brown, Editor(s)

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